1. Field of the Invention
The present invention relates to a device and a method for scrubbing and cleaning a substrate for the liquid crystal display (LCD) by brushes while applying a solution to the substrate.
2. Description of the Related Art
It is quite important in the course of making the LCDs to finish each glass substrate clean and smooth. For this purpose, both surfaces of the LCD glass substrate are scrubbed by brushes while applying cleaning solution to the substrate. Foreign substances such as particles and grains which have adhered to the surfaces of the substrate are thus removed from them. The scrubber is used to scrub the LCD glass substrate in this manner. The scrubber includes a mechanism for carrying the substrates successively and brushes made of soft fibers such as nylon or mohair.
Particles and grains firmly adhere to the surfaces of the glass substrate. It is therefore impossible to completely remove the particles from the substrate unless an extended scrubbing time is provided. In the case of the conventional scrubbers, the scrubbing time is made long by making the substrate carrying passage long and the substrate carrying speed low. When the substrate carrying passage is made long, however, the device must be made large in size. When the substrate carrying speed is made low, the scrubbing and cleaning efficiency becomes low.
The conventional device includes, as the mechanism for removing particles and grains from the substrate, a water jet cleaning mechanism for jetting high pressure water of higher than 100 Kg/cm.sup.2 to the substrate or a ultrasonic cleaning mechanism for supplying water, to which ultrasonic vibrations having a frequency of about 1 MHz have been applied, to the substrate.
However, in the case of the water jet cleaning mechanism it is difficult to make the flow rate of high pressure water jetted sufficiently large. The maximum flow rate achieved by the water jet cleaning mechanism is only about 0.5 l/min. The amount of water jetted is therefore insufficient to wash out particles and grains from the substrate only by jetted water. This makes it necessary to add a rinse mechanism to the water jet cleaning mechanism wherein a large amount of rinsing solution (or pure water) is supplied to the top surface of the substrate through the rinse mechanism to completely remove particles from it. Pure water having a pressure of 1-2 Kg/cm.sup.2 as supplied to the substrate at a flow rate of several litters per minute through the rinse mechanism.
Recently, the LCD glass substrates are becoming larger and larger in size. In addition, it is desired for the substrate processing capacity in each manufacturing section to become higher and for the productivity to become higher accordingly. The conventional techniques are insufficient to meet the needs. This asks the scrubbing and cleaning capacity to be made higher.